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| United States Patent |
5,342,920
|
|
Imai
, et al.
|
August 30, 1994
|
Process for the preparation of polyarylene sulfide and an apparatus for
the preparation thereof
Abstract
High molecular weight polyarylene sulfide prepared by reacting an alkali
metal sulfide with a dihaloaromatic compound in an organic amide solvent,
wherein a gaseous phase part of a reactor is cooled to thereby condense a
part of a gaseous phase in the reactor, and the condensed liquid is
refluxed to a liquid phase in the reactor. Higher molecular weight is
attained by copolymerization with 0.005 to 1.5 mole percent, based on the
alkali metal sulfide, of a polyhaloaromatic compound.
| Inventors:
|
Imai; Yoichi (Icihara, JP);
Hirano; Toshiyuki (Kimitsu, JP);
Komiyama; Osamu (Icihara, JP);
Yamanaka; Hidenori (Icihara, JP)
|
| Assignee:
|
Tonen Chemical Corporation (Tokyo, JP)
|
| Appl. No.:
|
992860 |
| Filed:
|
December 16, 1992 |
Foreign Application Priority Data
| Dec 17, 1991[JP] | 3-352990 |
| Oct 07, 1992[JP] | 4-291908 |
| Oct 07, 1992[JP] | 4-291909 |
| Nov 18, 1992[JP] | 4-331264 |
| Current U.S. Class: |
528/388; 422/138 |
| Intern'l Class: |
C08G 075/16 |
| Field of Search: |
528/388
422/138
|
References Cited
U.S. Patent Documents
| 4433138 | Feb., 1984 | Idel et al. | 528/388.
|
| 4645826 | Feb., 1987 | Iizuka et al. | 525/537.
|
| 5093469 | Mar., 1992 | Senga | 528/388.
|
| 5109110 | Apr., 1992 | Ogata | 528/388.
|
| 5194580 | Mar., 1993 | Koyama et al. | 528/388.
|
| Foreign Patent Documents |
| 0126369 | Feb., 1981 | EP.
| |
| 0065689 | Mar., 1983 | EP.
| |
Other References
Database WPI; Derwent Publications Ltd., London, GB, AN 80-23476 & SU-A-676
597 (Elementorganic Fusi) Jul. 30 1979 *abstract*.
European Search Report Application No. EP 92 20 3964 dated Mar. 29, 1993
and Communication No. 92203964.9 dated Apr. 22, 1993.
|
Primary Examiner: Marquis; Melvyn I.
Assistant Examiner: Lee; H.
Attorney, Agent or Firm: Kane, Dalsimer, Sullivan, Kurucz, Levy, Eisele and Richard
Claims
We claim:
1. A process for the preparation of polyarylene sulfide comprised of
conducting a polymerization reaction in a reactor provided with cooling
means by polymerizing an alkali metal sulfide with a dihaloaromatic
compound in an organic amide solvent, wherein a part of a gaseous phase in
the reactor is cooled by the cooling means to thereby condense part of a
gaseous phase in the reactor to a liquid, and the condensed liquid is
refluxed to a liquid phase in the reactor.
2. The process as claimed in claim 1, wherein the reaction is conducted in
at least two steps having different temperatures.
3. The process as claimed in claim 1, wherein 0.005 to 1.5 mole percent,
based on the alkali metal sulfide, of a polyhaloaromatic compound is
further reacted.
4. The process as claimed in claim 3, wherein a water content in a reaction
system is less than 1.7 mole per mole of the alkali metal sulfide.
5. The process as claimed in claim 3, wherein the reaction is conducted in
at least two steps having different temperatures.
Description
FIELD OF THE INVENTION
The present invention relates to a process for the preparation of
polyarylene sulfide, particularly high molecular weight polyarylene
sulfide, and an apparatus for the preparation thereof.
PRIOR ART
A basic process for the preparation of polyarylene sulfide (hereinafter
referred to as PAS) is known where a dihaloaromatic compound is reacted
with an alkali metal sulfide in an organic amide solvent (Japanese Patent
Publication No. 3368/1970). The PAS prepared in this process had a low
molecular weight and was, therefore, subjected to heat cross linking
treatment to thereby yield high molecular weight. However, it is difficult
to process the cross-linked PAS into films, sheets, fibers and the like.
Recently, high molecular weight PAS was made without heat cross linking.
Films, sheets, fibers and the like prepared from such PAS have excellent
mechanical properties. In injection molding, such PAS exhibits high
flowability under low shearing velocity in melt processing. Such PAS is
bright in color. For these reasons, a need for such PAS is increasing.
Various improved processes are known to prepare high molecular weight PAS
solely by polymerization.
In a process described in Japanese Patent Publication No. 12240/1977,
alkali metal carboxylates such as sodium acetate and lithium acetate are
used as a polymerization aid in a conventional reaction system. However,
production costs of PAS are higher in this process as a result and the
process is very unfavorable commercially. A great deal of incidental
facilities, technology and costs are required to separate and recover
those alkali metal carboxylates from a product, and dispose of those
without pollution, which makes the process further disadvantageous.
Japanese Patent Application Laid-Open (or Kokai) No. 7332/1986 discloses a
process for the preparation of high molecular weight PAS, which is
characterized in that reaction is conducted in two steps, and water is
added in the second step. That is, reaction is conducted at 180.degree. to
235.degree. C. in the presence of 0.5 to 2.4 moles of water per mole of
alkali metal sulfide to form PAS in a conversion of a dihaloaromatic
compound of 50 to 98 mole % in the first step. In the second step, water
is added and reaction is conducted at 245.degree. to 290.degree. C. in the
presence of 2.5 to 7.0 moles of water.
Many other processes are also known to produce high molecular weight PAS by
letting water present intentionally likewise. In a process described in
Japanese Patent Application Laid-Open No. 39926/1988, reaction is
conducted at 235.degree. to 280.degree. C. in the presence of 0.5 to 5
moles of water per kilogram of a solvent in a conversion of 70 to 98 mole
% in a first step. In a second step, water is added and reaction is
carried out at 240.degree. to 290.degree. C. in the presence of 6 to 15
moles of water. It is said that this process is characterized in that
reaction temperature is higher and a water content is less in the first
step, compared to those in the process of the aforesaid Japanese Patent
Application Laid-Open No. 7332/1986, and that a large amount of water is
added to cause liquid-liquid two layers separation in the second step.
A process is known where reaction is further performed after such
liquid-liquid two layers separation. That is, in a process described in
Japanese Patent Application Laid-Open No. 285922/1987, reaction is
conducted at 180.degree. to 235.degree. C. in the presence of 0.5 to 2.4
moles of water per mole of alkali metal sulfide in a conversion of at
least 80 mole % in a first step. In a second step, water is added and
reaction is conducted at 245.degree. to 290.degree. C. in the presence of
2.5 to 7.0 moles of water and, then, stirring is stopped to cause two
layers separation. In a third step, the lower layer (concentrated polymer
solution layer) is further subjected to reaction at 245.degree. to
350.degree. C.
Water must be added in the middle of reaction in the aforesaid processes
where a water content is changed in the middle of reaction to prepare high
molecular weight PAS. In order to do this, there are only three
alternatives, i.e., to once lower a temperature so as to reduce pressure
to normal pressure and then add water; to change a reactor between a first
step and a second step; or to inject water by pressure into a reactor
which is at high temperature and pressure. However, these operations are
disadvantageous in practice in terms of facilities, economy and
manipulation. Besides, sodium sulfide is usually used in a concentration
of 1 mole per 0.4 to 0.5 kg of a solvent (e.g. N-methyl pyrrolidone). When
2.5 moles or more of water per mole of sodium sulfide is present at a
temperature of 245.degree. C. or higher in a second step, pressure is so
high as 20 kg/cm.sup.2 G or more. Therefore, a reactor must resist
pressure of 30 kg/cm.sup.2 G or more in practice. Thus, it is impossible
to apply facilities which were built for previous processes where no water
is added in the middle course of reaction. Pressure resisting facilities
are comparatively costly. Accordingly, a process which may be practiced at
a lower pressure as previously is desirable. Further, operations at a
pressure as low as possible is preferred from a point of view of safety.
Moreover, it is said that a high mole ratio of alkali metal sulfide to a
dihaloaromatic compound, e.g., 0.980 to 1.01, is basically needed to
prepare high molecular weight PAS solely by polymerization. When a
polymerization temperature is raised at 230.degree. C. or higher, a
reaction system with a high mole ratio of alkali metal sulfide to a
dihaloaromatic compound is unstable and high molecular weight PAS is not
formed, or PAS once-formed may depolymerize to form lower molecular weight
polymers and a noticeable amount of thiophenol.
It is known to use a polyhaloaromatic compound having three or more halogen
substitutes in molecule to prepare high molecular weight PAS solely by
means of polymerization. In a process described in Japanese Patent
Publication 8719/1979, a polyhaloaromatic compound and lithium carboxylate
or lithium chloride are added in a conventional reaction system. Expensive
lithium carboxylate or lithium chloride should be used at an approximately
equimolar ratio to alkali metal sulfide, which increases production costs
of PAS and makes the process very disadvantageous commercially. Further, a
great deal of incidental facilities, technology and costs are required to
separate and recover lithium carboxylate or lithium chloride from a
product without pollution, which makes the process further
disadvantageous.
In a process described in Japanese Patent Publication 334/1982, a
polyhaloaromatic compound, about 1.2 to 2.4 moles of water (including
hydration water of alkali metal sulfide) per mole of alkali metal sulfide,
or about 1.0 to 2.4 moles of water and sodium carboxylate are added in a
conventional reaction system. According to the Examples, in the case where
sodium carboxylate is not added, sufficiently high molecular weight PAS is
not obtained unless at least 1.5 moles of water is present. When a water
content in a system is so high, pressure in a reactor during reaction is
high, which requires a high pressure-resisting reactor and, therefore,
increases costs. On the other hand, in the case where sodium carboxylate
is added, incidental facilities and technology are required to separate
and recover it from a product and dispose of it without pollution, which
increases costs.
SUMMARY OF THE INVENTION
A purpose of the invention is to provide an economical and convenient
process for the preparation of high molecular weight polyarylene sulfide,
wherein an expensive polymerization aid such as alkali metal carboxylates
and lithium chloride are unnecessary, and polymerization is carried out
with a constant, comparatively low water content in a reaction system in a
low pressure reactor without necessity for incidental facilities such as a
pressure injection device.
Another purpose of the invention is to provide an apparatus for the
preparation of high molecular weight polyarylene sulfide.
The present inventors have closely examined polymerization mechanism in
order to solve the aforesaid problems on the preparation of high molecular
weight polyarylene sulfide, and have found that the aforesaid problems are
solved by cooling a gaseous phase part of a reactor, whereby
depolymerization of a formed polyarylene sulfide is also avoided.
The present invention is a process for the preparation of polyarylene
sulfide by reacting an alkali metal sulfide with a dihaloaromatic compound
in an organic amide solvent, characterized in that a gaseous phase part of
a reactor is cooled to thereby condense a part of a gaseous phase in the
reactor, and the condensed liquid is refluxed to an upper liquid phase in
the reactor.
Preferably, 0.005 to 1.5 mole percent, based on the alkali metal sulfide,
of a polyhaloaromatic compound is copolymerized to attain higher molecular
weight polyarylene sulfide.
The invention also provides an apparatus for the preparation of polyarylene
sulfide by the reaction of an alkali metal sulfide with a dihaloaromatic
compound in an organic amide solvent, characterized in that the apparatus
is provided with a means of cooling a gaseous phase part of a reactor to
thereby condense a part of a gaseous phase in the reactor, and returning
the condensed liquid to an upper liquid phase in the reactor.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of a reactor unit with an external cooling coil.
FIG. 2 is a schematic view of a reactor unit with an internal cooling coil.
FIG. 3 is a schematic view of a reactor unit with a coolant jacket.
FIG. 4 is a schematic view of a reactor unit with a for spraying a liquid.
FIG. 5 is a schematic view of a reactor unit with a unit for blowing a gas.
DETAILED DESCRIPTION OF THE INVENTION
The condensed anti refluxed liquid has a higher water content compared to
the liquid phase bulk, because of difference of vapor pressure between
water and an amide solvent. This reflux with a higher water content
creates a layer having a higher water content in the upper part of the
reaction mixture. As a result, larger amounts of remaining alkali metal
sulfide (e.g., Na.sub.2 S), alkali metal halide (e.g., NaCl) and oligomers
are contained in this layer. In conventional processes, formed polyarylene
sulfide, starting materials such as Na.sub.2 S and by-products are mixed
together homogeneously at a high temperature of 230.degree. C. or higher.
In such conditions, high molecular weight polyarylene sulfide is not
formed and, moreover, even once formed polyarylene sulfide may be
depolymerized to form lower molecular weight polymers and a noticeable
amount of thiophenol as by-products. In the invention, it is believed that
the aforesaid unfavorable phenomena may be avoided, factors which
interfare with reaction may be excluded very effectively and high
molecular weight polyarylene sulfide may be obtained by actively cooling
the gaseous phase part of a reactor and returning a large amount of
water-rich reflux to the upper part of the liquid phase. However, the
invention should not be restricted by effects attained only by the
aforesaid phenomena, but various effects cause by cooling the gaseous
phase part may give to high molecular weight polyarylene sulfide.
Addition of water in the middle course of reaction is unnecessary in the
invention, unlike in conventional processes, but such addition of water is
not precluded. However, some of the advantages of the invention will be
lost with operations of adding water. Accordingly, it is preferred that
the whole water content in a polymerization system is constant in the
course of reaction.
In general, polymerization of polyarylene sulfide is conducted in a
temperature range of from 180.degree. to 350.degree. C., and a reactor
must be heated. Accordingly, it was common to cover a reactor or a whole
reaction apparatus with heat insulating materials for heat economy. In
contrast, the gaseous phase part of a reactor is rather cooled in the
invention. This is, of course, disadvantageous in heat economy, compared
to the conventional ways, but the attained advantages more than make up
for the disadvantage. A means of cooling the gaseous phase part of a
reactor may be of external cooling or internal cooling, and preferably
comprises (a) an external cooling coil coiled on an upper outer wall of
the reactor, (b) an internal cooling coil mounted in an upper internal
part of the reactor, (c) a coolant jacket mounted on an upper outer wall
of the reactor, (d) a unit for spraying or blowing a liquid or gas
directly to an upper outer wall of the reactor, or (e) a reflux condenser
mounted, for instance, above the reactor. Any other means may also be
applied as long as they have an effect of increasing an amount of a reflux
in the reactor. It is unnecessary for such a cooling means to extend to
the whole gaseous phase part of the reactor. If the cooling effect extends
down to the liquid phase part, heat economy will be worsened. Accordingly,
it is preferred to cool only an upper gaseous phase part and this is
sufficient. When a surrounding temperature is comparatively low (e.g.
normal temperature), proper cooling may be done by removing heat
insulating materials from the upper part of a conventional reactor.
A water/amide solvent mixture condensed on the wall of a reactor or the
wall of an interal cooling means may fall down along the wall to reach the
upper part of the liquid phase in a reactor, or may be collected in any
manner and led to the upper part of the liquid phase in a reactor.
Meanwhile, the temperature of a liquid phase bulk is maintained constant at
a predetermined value, or controlled in accordance with a predetermined
temperature profile. In the case where the temperature is constant,
reaction is preferably carried out at a temperature of 230.degree. to
275.degree. C. for 0.1 to 20 hours, more preferably 240.degree. to
265.degree. C. for 1 to 6 hours. It is advantageous to apply a reaction
temperature prefile having at least two steps in order to obtain higher
molecular weight polyarylene sulfide. The first step is preferably
conducted at a temperature of 195.degree. to 240.degree. C. If the
temperature is lower, a reaction rate is too late to be practical. If it
exceeds 240.degree. C., a reaction rate is too fast to obtain sufficiently
high molecular weight polyarylene sulfide and, moreover, a rate of side
reaction increases noticeably. The first step is preferably ended at a
time when a ratio of the remaining dihaloaromatic compound to the charged
one in the polymerization system is 1 to 40 mole % and the molecular
weight reaches a range of from 3,000 to 20,000, more preferably 2 to 15
mole % and a molecular weight range of from 5,000 to 15,000. If the ratio
exceeds 40 mole %, side reacton such as depolymerization tends to occur in
a subsequent second step. If it is less than 1 mole %, it is difficult to
obtain high molecular weight polyarylene sulfide finally. Then, the
temperature is increased and, in a final step, reaction is preferably
carried out at a reaction temperature of 240.degree. to 270.degree. C. for
1 to 10 hours. If the temperature is lower, sufficiently high molecular
weight polyarylene sulfide cannot be obtained. If the temperature exceeds
270.degree. C., side reaction such as depolymerization tends to occur and
it is difficult to stably prepare high molecular weight product.
In practice, a water content in alkali metal sulfide in an amide solvent is
brought to a predetermined value by dehydration or addition of water at
need in an atmosphere of inert gas. The water content is preferably 0.5 to
2.5 moles per mole of alkali metal sulfide. If it is less than 0.5 mole,
the reaction rate is too fast and unfavorable reaction such as side
reaction may occur. If it exceeds 2.5 moles, the reaction rate is too slow
and, moreover, larger amounts of by-products such as phenol are seen in a
filtrate after the reaction and a polymerization degree is smaller. A
dihaloaromatic compound may be introduced in a reaction system at the
beginning, or may be added during or after the adjustment of the water
content. It is preferably used in an amount of 0.9 to 1.1 moles per mole
of alkali metal sulfide to obtain high molecular weight polyarylene
sulfide.
In the case of one step reaction at a constant temperature, cooling of the
gaseous phase part during reaction should be started, at latest, below
250.degree. C. in the middle course of temperature rise, but preferably
started at the beginning of reaction. In the case of multi steps reaction,
the cooling is preferably started in the middle course of temperature rise
after a first step reaction, but more desirably started in a first step
reaction. Pressure in a reactor is usually a most proper measure for a
degree of a cooling effect. An absolute value of pressure depends upon
characteristics of a reactor, stirring conditions, water content in a
reaction system, mole ratio of a dihaloaromatic compound to alkali metal
sulfide and so on. However, decreased reactor pressure, compared to that
in the same reaction conditions except the absence of cooling, means that
the amount of a reflux is increased and the temperature at the gas-liquid
interface of a reaction solution is lowered. It is thought that a relative
decrease in pressure indicates extent of separation between a layer with a
larger water content and the remaining layer. Accordingly, the cooling
should be done to such extent that an internal pressure in a reactor is
lower than that of the case where the cooling is not conducted. A person
skilled in the art may determine the extent of cooling, depending upon
equipments used and operation conditions.
Polyarylene sulfide thus prepared may be separated from by-products and
dried in known making-up procedures.
The invention will be explained in reference to the accompanying figures.
FIG. 1 shows a reactor unit having a cooling coil wound on an upper
external of a reactor. Materials for reaction are fed into a reactor 1 via
conduit 8 to form a liquid phase which is stirred with a stirring means 2.
The liquid phase part of the reactor 1 is covered with a heat medium
jacket 3 where a heat medium flows in via conduit 4 and flows out via
conduit 5. In the liquid phase part of the reactor, internal heating coil
6 is installed, in which a heat medium flows in and flows out. In the
upper part of the reactor, nitrogen is introduced for pressurization via
conduit 8, and drawn out for depressurization via conduit 8 again. When
heat dehydration is carried out after sodium sulfide is charged, suction
is applied via conduit 8. After completion of polymerization, a slurry
containing polyarylene sulfide formed is drawn out via coduit 9.
On the upper external wall of the reactor, an external cooling coil 11 is
wounded, in which a coolant of, for instance, 20.degree. to 90.degree. C.,
e.g. water, is introduced via conduit 13, under flow rate control by a
control valve (not shown), and drawn out via conduit 12. Thus, the gaseous
phase part (i.e. upper part) of the reactor is cooled, and a part of the
gaseous phase is condensed, falls down along the wall of the reactor and
refluxed into the liquid phase. The whole reactor is covered with heat
insulating material 10.
FIG. 2 shows another embodiment where internal cooling coil 21 is installed
in an upper inner part of a reactor 1. Numerals in FIG. 2 indicate the
same parts as in FIG. 1. This applied to other figures. Liquid condensed
on the surface of cooling coil 21 falls down along the cooling coil and
then along the wall of the reactor and reaches a liquid phase.
Alternatively, a trough may be arranged so as to receive falling droplets
condensed on the surface of cooling coil 21 and introduce them to a liquid
phase.
In another embodiment shown in FIG. 3, coolant jacket 31 is mounted on an
upper outer wall of reactor 1.
In another embodiment shown in FIG. 4, water is supplied via conduit 42 and
sprayed via nozzles 41 directly to the upper outer wall of reactor 1. The
sprayed water flows down slowly in a porous support for a heat insulating
material, 44, for instance, spongy layer made of stainless steel, and is
drawn via conduit 43.
In another embodiment shown in FIG. 5, there is no heat insulating material
on the upper part of reactor 1, where the wall of the reactor is exposed.
Pressurized air is supplied via conduit 52, and blown via nozzles 51 to
the upper external wall of the reactor.
A slurry containing polyphenylene sulfide prepared in the apparatus
according to the invention is taken out via conduit 9, separated from
by-products in conventional steps, and dried.
Amide solvents to be used in the invention are those known for
polymerization of polyphenylene sulfide and include, for instance,
N-methyl pyrrolidone (hereinafter, NMP), N, N-dimethyl formamide, N,
N-dimethyl acetamide, N-methyl caprolactame and the like, and mixtures
thereof with NMP being preferred. All of these have vapor pressure lower
than that of water.
Alkali metal sulfides to be used in the invention are also known and
include, for instance, lithium sulfide, sodium sulfide, potassium sulfide,
rubidium sulfide and mixtures thereof. These may be hydrated or in a form
of aqueous solution. Alternatively, hydrosulfides or hydrates thereof
corresponding to these may be converted into the corresponding sulfides
with each corresponding hydroxide and used. Sodium sulfide which is less
expensive is preferred.
Dihaloaramatic compounds to be used in the invention may be selected from
ones described in Japanese Patent Publication 3368/1970. p-Dichlorobenzene
is preferred. Further, a small amount (20 mole % or less) of one or more
of m-dihobenzen, o-dihalobenzen, dihalogenated dyphenyl ether, diphenyl
sulfone and biphenyl may be used to prepare copolymers, such as
m-dichlorobenzene, o-dichlorobenzene, p,p'-dichlorodiphenyl ether,
m,p'-dichlorodiphenyl ether, m,m'-dichlorodiphenyl ether,
p,p'-dichlorodiphenyl sulfone, m,p'-dichlorodiphenyl sulfone,
m,m'-dichlorodiphenyl sulfone, p,p'-dichlorobipheny1,
m,p'-dichlorobiphenyl and m,m'-dichlorobiphenyl.
Small amounts of additives, such as monohalogenated compounds as an end
group terminator or modifier, may be used.
Preparation of Higher Molecular Weight Polyarylene Sulfide With A
Polyhaloaromatic Compound
Higher molecular weight polyarylene sulfide is prepared by adding a
polyhaloaromatic compound as a comonomer in a reaction system in the
present invention.
In this embodiment, a whole water content in a reaction system is
preferably less than 1.7 moles, more preferably 0.8 to 1.2 moles, per mole
of alkali metal sulfide. If it exceeds 1.7 moles, side reactions occur
noticeably. Amounts of by-products, such as phenol, in a reaction product
increases with the increasing water content of the reaction system.
Polymerization degree is low, too. If the water content is less than 0.8
mole, a reaction rate is too fast to attain desired higher molecular
weight.
A polyhaloaromatic compound is used in an amount of 0.005 to 1.5 mole %,
preferably 0.02 to 0.75 mole %, based on alkali metal sulfide. If it is
less than 0.005 mole %, the effect of addition of a polyhaloaromatic
compound is not seen. If it exceeds 1.5 mole %, viscosity of polyarylene
sulfide at melt is extremely high. Therefore, gel-like substances appear
in molding and, further, moldability is poor. The polyhaloaromatic
compound may be added together with a dihaloaromatic compound in a
reaction system, or may be added any time in the middle course of
reaction.
Polyhaloaromatic compounds to be used in the invention have at least three
halogen substitutes in molecule and include, for instance,
1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, 1,3,5-trichlorobenzene,
1,3-dichloro-5-bromobenzene, 2,4,6-trichlorotoluene,
1,2,3,5-tetrabromobenzene, hexachlorobenzene,
1,3,5-trichloro-2,4-6trimethylbenzene, 2,2',4,4'-tetrachlorobiphenyl,
2,2',6,6'-tetrabromo-3,3',5,5'-tetramethylbiphenyl,
1,2,3,4-tetrachloronaphthalene, 1,2,4-tribromo-6-methylnaphthalene, and
mixtures thereof. 1,2,4-trichlorobenzene and 1,3,5-trichlorobenzene are
preferred. and mixtures thereof. 1,2,4-trichlorobenzene and
1,3,5-trichlorobenzene are preferred.
EXAMPLE
The invention will be further explained hereinafter in reference to the
following Examples.
In the Examples and Comparison Examples, a molecular weight is a peak-top
molecular weight which is obtained as follows: a retention time determined
at 210.degree. C. in gel permeation chromatography using 1-chloro
naphthalene as a mobile phase is converted into a molecular weight based
on standard polystyrene which is then compensated in the Universal
Calibration Method. The apparatus used was type SSC-7000 available from
Senshu Kagaku. However, a weight average molecular weight was given in
place of a peak-top molecular weight in Examples 9 to 16 and Comparison
Examples 7 to 11.
EXAMPLE 1
In a 150 liters autoclave provided with an external cooling coil as shown
in FIG. 1 were charged 19 . 253 kg of flaky sodium sulfide (Na.sub.2 S
content of 60.8% by weight) and 45.0 kg of N-methyl-2-pyrrolidone
(hereinafter referred to as NMP). The temperature was elevated to
204.degree. C. in a flow of nitrogen under stirring to distill off 4.442
kg of water. The autoclave was then sealed and cooled to 180.degree. C.,
in which 21.940 kg of para- dichloro benzene (hereinafter referred to as
p-DCB) and 18.0 kg of NMP were charged. After pressurizing it to 1
kg/cm.sup.2 G (i.e., gauge pressure) with nitrogen gas at a liquid
temperature of 150.degree. C., the temperature was raised. Stirring was
continued at a liquid temperature of 220.degree. C. for three hours, while
a coolant of 20.degree. C. was passed in a coil which was wound on the
upper part of the outside of the autoclave to cool it. Then, the liquid
temperature was raised and stirring was continued at a liquid temperature
of 260.degree. C. for three hours. Subsequently, the temperature was
lowered and, at the same time, the cooling of the upper part of the
autoclave was stopped. The maximum pressure during the reaction was 8.71
kg/cm.sup.2 G.
The slurry obtained was filtered and washed with warm water repeatedly in a
conventional method, and then dried at 120.degree. C. for 4.5 hours to
obtain a white powdery product. The molecular weight of the polyphenylene
sulfide thus obtained was 42,000. The conversion, 100- (weight of p-DCB
remained/weight of p-DCB charged).times.100, was 98.4 Thiophenol was not
detected in the reaction product. The detection of thiophenol was
conducted by gas chromatography.
EXAMPLE 2
In a 4 m.sup.3 autoclave provided with water sprinkling nozzles as shown in
FIG. 4 were charged 513.4 kg of flaky sodium sulfide (Na.sub.2 S content
of 60.3% by weight) and 1190 kg of NMP. The temperature was elevated to
204.degree. C. in a flow of nitrogen under stirring to distill off 111.3
kg of water. The autoclave was then sealed and cooled to 180.degree. C.,
in which 583.1 kg of p-DCB and 400 kG of NMP were charged. After
pressurizing it to 1 kg/cm.sup.2 G with nitrogen gas at a liquid
temperature of 150.degree. C., the temperature was raised. Stirring was
continued at a liquid temperature of 215.degree. C. for five hours, while
water was sprinkled to the upper part of the autoclave to cool it. Then,
the temperature was raised and stirring was continued at a liquid
temperature of 255.degree. C. for four hours. The temperature was lowered
and, at the same time, the cooling of the upper part of the autoclave was
stopped. The maximum pressure during the reaction was 9.2 kg/cm.sup.2 G.
The slurry obtained was filtered and washed with warm water repeatedly in a
conventional method, and then dried in a dryer of 130.degree. C. to obtain
a white powdery product. The molecular weight of the polyphenylene sulfide
thus obtained was 46,500. The conversion was 98.6%. Thiophenol was not
detected in the reaction product.
EXAMPLE 3
In a 150 liters autoclave provided with eight air-blowing nozzles as shown
in FIG. 5 were charged 19.253 kg of flaky sodium sulfide (Na.sub.2 S
content of 60.8% by weight) and 45.0 kg of NNP. The temperature was
elevated to 204.degree. C. in a flow of nitrogen under stirring to distill
off 4.074 kg of water. The autoclave was then sealed and cooled to
180.degree. C., in which 21.940 kg of p-DCB and 18.0 kg of NMP were
charged. After pressurizing it to 1 kg/cm.sup.2 G with nitrogen gas at a
liquid temperature of 150.degree. C., the temperature was raised. After
the liquid temperature reached 240.degree. C., an air flow of 15.degree.
C. was blown at a flow rate of 20 liters/min. via. eight nozzles to the
upper part of the autoclave in which a heat insulating material was
removed. Stirring was continued at a liquid temperature of 250.degree. C.
for two hours. The temperature was lowered and, at the same time, the
cooling of the upper part of the autoclave was stopped. The maximum
pressure during the reaction was 8.89 kg/cm.sup.2 G.
The slurry obtained was filtered and washed with warm water repeatedly in a
conventional method, and then dried at 120.degree. C. for 4.5 hours to
obtain a white powdery product. The molecular weight of the polyphenylene
sulfide thus obtained was 30,300. The conversion was 98.6% Thiophenol was
not detected in the reaction product.
COMPARISON EXAMPLE 1
Polymerization was carried out as in Example 1 with the exception that no
coolant was passed in the external cooling coil. The maximum pressure
during the reaction was 10.3 kg/cm.sup.2 G. The polymer obtained had a
molecular weight of 27,500 and the conversion was 99.0%. It was found that
thiophenol was present in a concentration of 200 ppm in the reaction
product.
COMPARISON EXAMPLE 2
Polymerization was carried out as in Example 1 with the exception that a
heating medium of 270.degree. C. was passed in the external cooling coil.
The maximum pressure during the reaction was 11.2 kg/cm.sup.2 G. The
polymer obtained had a molecular weight of 22,000 and the conversion was
99.1% The polymer obtained was little brownish white powder. It was found
that thiophenol was present in a concentration of 400 ppm in the reaction
product.
COMPARISON EXAMPLE 3
The same procedure as in Example 2 was repeated with the exception that
water was not sprinkled to the upper part of the autoclave. The maximum
pressure during the reaction was 10.8 kg/cm.sup.2 G. The polymer obtained
had a molecular weight of 23,500 and the conversion was 99.0%. It was
found that thiophenol was present in a concentration of 250 ppm in the
reaction product.
EXAMPLE 4
In a 3 liters autoclave provided with air-blowing nozzles as shown in FIG.
5 were charged 388.3 g of flaky sodium sulfide (Na.sub.2 S content of 60.3
% by weight) and 900 g of NMP. The temperature was elevated to 204.degree.
C. in a flow of nitrogen under stirring to distill off 81.2 g of water.
The autoclave was then sealed and cooled to 180.degree. C., to which a
solution of 436.6 g of p-DCB and 4.4 g of meta-dichloro benzene dissolved
in 240 g of NMP was added. After pressurizing it to 1 kg/cm.sup.2 G with
nitrogen gas at a liquid temperature of 150.degree. C., the temperature
was raised. Stirring was continued at a liquid temperature of 215.degree.
C. for 5.5 hours, while an air flow was blown via four nozzles to the
upper part of the autoclave to cool it. Then, the temperature was raised
and stirring was continued at a liquid temperature of 250.degree. C. for
three hours. Subsequently, the temperature was lowered and, at the same
time, the cooling of the upper part of the autoclave was stopped. The
maximum pressure during the reaction was 8.18 kg/cm.sup.2 G.
The slurry obtained was filtered and washed with warm water repeatedly in a
convent tonal method, and then dried in an oven of 120.degree. C. for 5
hours to obtain a white powdery product. The molecular weight of the
product was 37,600. The conversion was 98.8%. Thiophenol was not detected
in the reaction product.
COMPARISON EXAMPLE 4
The same procedure as in Example 3 was repeated with the exception that the
air flow was not blown to the upper part of the autoclave which part was
covered with a heat insulating material. The maximum pressure during the
reaction was 10.8 kg/cm.sup.2 G. The polymer obtained had a molecular
weight of 26,500 and the conversion was 98.9%. It was found that
thiophenol was present in a concentration of 140 ppm in the reaction
product.
EXAMPLE 5
In a 4 m.sup.3 autoclave provided with water-sprinkling nozzles as shown in
FIG. 4 were charged 513.4 kg of flaky sodium sulfide (Na.sub.2 S content
of 60.8% by weight) and 1190 kg of NMP. The temperature was elevated to
204.degree. C. in a flow of nitrogen under stirring to distill off 111.3
kg of water. The autoclave was then sealed and cooled to 180.degree. C.,
in which 583.1 kg of p-DCB and 400 kg of NMP were charged. After
pressurizing it to 1 kg/cm.sup.2 G with nitrogen gas at a liquid
temperature of 150.degree. C., the temperature was raised. After the
liquid temperature reached 240.degree. C., water was sprinkled to the
upper part of the autoclave to cool it. Then the temperature was raised
and stirring was continued at a liquid temperature of 255.degree. C. for
two hours. Subsequently, the temperature was lowered and, at the same
time, the cooling of the upper part of the autoclave was stopped. The
maximum pressure during the reaction was 9.4 kg/cm.sup.2 G.
The slurry obtained was filtered and washed with warm water repeatedly in a
conventional method, and then dried in a dryer of 130.degree. C. to obtain
a white powdery product. The molecular weight of the polyphenylene sulfide
thus obtained was 31,500. The conversion was 99.1%. Trace of thiophenol
was detected in the reaction product.
COMPARISON EXAMPLE 5
The same procedure as in Example 5 was repeated with the exception that
water was not sprinkled to the upper part of the autoclave. The maximum
pressure during the reaction was 11.0 kg/cm.sup.2 G. The polymer obtained
had a molecular weight of 23,800 and the conversion was 99.3%. It was
found that thiophenol was present in a concentration of 220 ppm in the
reaction product.
EXAMPLE 6
A 4 m.sup.3 autoclave was used. Its upper external part above a liquid
level was not covered with a heat insulating material and exposed to air.
An atmospheric temperature was 20.3.degree. C. The lower external part
below a liquid level was covered with a heating jacket which was in turn
covered with refractory bricks for thermal insulation. In the above
autoclave were charged 512.2 kg of flaky sodium sulfide (Na.sub.2 S
content of 60.3% by weight ) and 1200 kg of NMP. The temperature was
elevated to 204.degree. C. in a flow of nitrogen under stirring to distill
off 104.1 kg of water. The autoclave was then sealed and cooled to
180.degree. C., in which 577.4 kg of p-DCB and 400 kg of NMP were charged.
After pressurizing it to 1 kg/cm.sup.2 G with nitrogen gas at a liquid
temperature of 150.degree. C., the temperature was raised. Stirring was
continued at a liquid temperature of 215.degree. C. for five hours. Then,
the temperature was raised and stirring was continued at a liquid
temperature of 255.degree. C. for four hours. Subsequently, the
temperature was lowered. The maximum pressure during the reaction was 9.8
kg/cm.sup.2 G.
The molecular weight of a white powdery product thus obtained was 41,700.
The conversion was 98.7%. Thiophenol was detected in a concentration of 20
ppm in the reaction product.
COMPARISON EXAMPLE 6
The same procedure as in Example 6 was repeated with the except ion that
the whole reaction apparatus was heat insulated with refractory bricks.
The maximum pressure during the reaction was 10.3 kg/cm.sup.2 G. The
slurry obtained was filtered and washed with warm water repeatedly in a
conventional method, and then dried in a dryer of 130.degree. C. to obtain
a white powdery product. The molecular weight of the polyphenylene sulfide
thus obtained was 25,000. The conversion was 99.1%. Thiophenol was
detected in a concentration of 280 ppm in the reaction product.
EXAMPLE 7
In a 150 liters autoclave provided with an internal cooling coil as shown
in FIG. 2 were charged 16.825 kg of flaky sodium sulfide (Na.sub.2 S
content of 60.3% by weight) and 39.0 kg of NMP. The temperature was
elevated to 204.degree. C. in a flow of nitrogen under stirring to distill
off 3.627 kg of water. The autoclave was then sealed and cooled to
180.degree. C., in which 19.206 kg of p-DCB and 15.6 kg of NMP were
charged. After pressurizing it to 1 kg/cm.sup.2 G with nitrogen gas at a
liquid temperature of 150.degree. C., the temperature was raised.
Stirring was continued for 6 hours while a liquid temperature was
maintained at 215.degree. C., and then the temperature was raised again.
After the temperature reached 220.degree. C., a coolant of 20.degree. C.
was passed in the internal cooling coil. The liquid temperature was raised
up to 250.degree. C. and stirring was continued at that temperature for 3
hours. Subsequently, the temperature was lowered and, at the same time,
the flow of the coolant in the internal cooling coil was stopped. The
maximum pressure during the reaction was 8.61 kg/cm.sup.2 G.
The slurry obtained was treated as in Example 1 to obtain a white powdery
product. The molecular weight of the polyphenylene sulfide thus obtained
was 44,500. The conversion was 99.2%. Thiophenol was not detected in the
reaction product.
COMPARISON EXAMPLE 7
Polymerization was carried out as in Example 7 with the exception that no
coolant was passed in the internal cooling coil. The maximum pressure
during the reaction was 10.9 kg/cm.sup.2 G. The polymer thus obtained had
a molecular weight of 27,000 and the conversion was 98.8%. It was found
that thiophenol was present in a concentration of 175 ppm in the reaction
product.
EXAMPLE 8
In a 2 m.sup.3 autoclave provided with a coolant jacket as shown in FIG. 3
were charged 256.7 kg of flaky sodium sulfide (Na.sub.2 S content of 60.8%
by weight ) and 600 kg of NMP. The temperature was elevated to 204.degree.
C. in a flow of nitrogen under stirring to distill off 57.6 kg of water.
The autoclave was then sealed and cooled to 180.degree. C., in which 293.1
kg of p-DCB and 200 kg of NMP were charged. After pressurizing it to 1
kg/cm.sup.2 G with nitrogen gas at a liquid temperature of 150.degree. C.,
the temperature was raised. Stirring was continued at a liquid temperature
of 20.degree. C. for 4.5 hours, while a coolant of 20.degree. C. was
passed in the jacket. Then, the liquid temperature was raised and stirring
was continued at a liquid temperature of 255.degree. C. for three hours.
Subsequently, the temperature was lowered and, at the same time, the
cooling of the upper part of the autoclave was stopped. The maximum
pressure during the reaction was 8.55 kg/cm.sup.2 G.
The slurry obtained was filtered and washed with warm water repeatedly in a
conventional method, and then dried in a dryer of 130.degree. C. to obtain
a white powdery product. The molecular weight of the polyphenylene sulfide
thus obtained was 48,300. The conversion was 98.9%. Thiophenol was not
detected in the reaction product.
EXAMPLE 9
In a 150 liters autoclave as shown in FIG. 4 were charged 19.478 kg of
flaky sodium sulfide (Na.sub.2 S content of 60.1% by weight) and 45.0 kg
of NMP. The temperature was elevated to 204.degree. C. in a flow of
nitrogen under stirring to distill off 4.856 kg of water (the content of
water remained being 1.08 moles per mole of sodium sulfide). The autoclave
was then sealed and cooled to 180.degree. C., in which 21.940 kg of p-DCB
and 18. 0 kg of NMP were charged. After pressurizing it to 1 kg/cm.sup.2 G
with nitrogen gas at a liquid temperature of 150.degree. C., the
temperature was raised. Stirring was continued at a liquid temperature of
215.degree. C. for 7 hours, while water was sprinkled on the upper part of
the outside of the autoclave to cool a gas phase part of the autoclave.
Then, 108.9 g of 1,3,5-trichlorobenzene (about 0.4 mole % based on sodium
sulfide) in 500 g of NMP were introduced into the autoclave by pressure
with a small high pressure pump. Then, the temperature was raised and
stirring was continued at a liquid temperature of 260.degree. C. for three
hours. Subsequently, the temperature was lowered and, at the same time,
the sprinkling of water on the upper part of the autoclave was stopped.
The maximum pressure during the reaction was 8.89 kg/cm.sup.2 G.
The slurry obtained was filtered and washed with warm water repeatedly in a
conventional method, and then dried in an oven of 120.degree. C. for 5
hours to obtain a white powdery product. The weight average molecular
weight of the polyphenylene sulfide thus obtained was 81,600. The
conversion was 99.0%. Thiophenol was not detected in the reaction product.
EXAMPLE 10
The same procedure as in Example 9 was repeated with the exception that
21.8 g of 1,3,5-trichlorobenzene (about 0.08 mole % based on sodium
sulfide) was used. The maximum pressure during the reaction was 8.87
kg/cm.sup.2 G. The weight average molecular weight of the white powdery
polyphenylene sulfide obtained was 51,500. The conversion was 99.2%.
Thiophenol was not detected in the reaction product.
EXAMPLE 11
In a 150 liters autoclave as shown in FIG. 5 were charged 19.478 kg of
flaky sodium sulfide (Na.sub.2 S content of 60.1% by weight) and 45.0 kg
of NMP. The temperature was elevated to 204.degree. C. in a flow of
nitrogen under stirring to distill off 5.180 kg of water (the content of
water remained being 0.96 mole per mole of sodium sulfide). The autoclave
was then sealed and cooled to 180.degree. C., in which 21.940 kg of p-DCB
and 18.0 kg of NMP were charged. After pressurizing it to 1 kg/cm.sup.2 G
with nitrogen gas at a liquid temperature of 150.degree. C., the
temperature was raised. Stirring was continued at a liquid temperature of
215.degree. C. for 7 hours, while a coolant of 20.degree. C. was passed in
a coil which was attached to the upper part of the outside of the
autoclave to cool a gas phase part of the autoclave. Then, 108.9 g of
1,2,4-trichlorobenzene (about 0.4 mole % based on sodium sulfide) in 500 g
of NMP were introduced into the autoclave by pressure with a small high
pressure pump. Then, the temperature was raised and stirring was continued
at a liquid temperature of 260.degree. C. for three hours. Subsequently,
the temperature was lowered and, at the same time, the cooling of the
upper part of the autoclave was stopped. The maximum pressure during the
reaction was 8.71 kg/cm.sup.2 G.
The slurry obtained was filtered and washed with warm water repeatedly in a
conventional method, and then dried in an oven of 120.degree. C. for 5
hours to obtain a white powdery product. The weight average molecular
weight of the polyphenylene sulfide thus obtained was 77,200. The
conversion was 99.1%. Thiophenol was not detected in the reaction product.
EXAMPLE 12
The same procedure as in Example 11 was repeated with the exception that
40.8 g of 1,2,4-trichlorobenzene (about 0.15 mole % based on sodium
sulfide) was used. The maximum pressure during the reaction was 8.73
kg/cm.sup.2 G. The weight average molecular weight of the white powdery
polyphenylene sulfide obtained was 56,700. The conversion was 99.2%.
Thiophenol was not detected in the reaction product.
EXAMPLE 13
In a 150 liters autoclave as shown in FIG. 1 were charged 19.478 kg of
flaky sodium sulfide (Na.sub.2 S content of 60.1% by weight) and 45.0 kg
of NMP. The temperature was elevated to 204.degree. C. in a flow of
nitrogen under stirring to distill off 5.072 kg of water (the content of
water remained being 1.0 mole per mole of sodium sulfide). The autoclave
was then sealed and cooled to 180.degree. C., in which 21.984 kg of p-DCB,
18.0 kg of NMP and 40.8 g of 1,2,4-trichlorobenzene (about 0.15 mole %
based on sodium sulfide) were charged. After pressurizing it to 1
kg/cm.sup.2 G with nitrogen gas at a liquid temperature of 150.degree. C.,
the temperature was raised. Stirring was continued at a liquid temperature
of 215.degree. C. for 7 hours, while a coolant of 20.degree. C. was passed
in a coil which was attached to the upper part of the outside of the
autoclave to cool a gas phase part of the autoclave. Then, the temperature
was raised and stirring was continued at a liquid temperature of
260.degree. C. for three hours. Subsequently, the temperature was lowered
and, at the same time, the cooling of the upper part of the autoclave was
stopped. The maximum pressure during the reaction was 8.69 kg/cm.sup.2 G.
The slurry obtained was filtered and washed with warm water repeatedly in a
conventional method, and then dried in an oven of 120.degree. C. for 5
hours to obtain a white powdery product. The weight average molecular
weight of the polyphenylene sulfide thus obtained was 60,800. The
conversion was 99.1%. Thiophenol was not detected in the reaction product.
EXAMPLE 14
The same procedure as in Example 13 was repeated with the exception that
54.5 g of 1,3,5-trichlorobenzene (about 0.2 mole % based on sodium
sulfide) was used in place of 1,2,4-trichlorobenzene. The maximum pressure
during the reaction was 8.72 kg/cm.sup.2 G. The weight average molecular
weight of the white powdery polyphenylene sulfide obtained was 70,800. The
conversion was 98.8%. Thiophenol was not detected in the reaction product.
EXAMPLE 15
In a 4 m.sup.3 autoclave as shown in FIG. 4 were charged 512. 9 kg of flaky
sodium sulfide (Na.sub.2 S content of 60.1% by weight) and 1200 kg of NMP.
The temperature was elevated to 204.degree. C. in a flow of nitrogen under
stirring to distill off 131.6 kg of water (the content of water remained
being 1.05 mole % per mole of sodium sulfide). The autoclave was then
sealed and cooled to 180.degree. C., in which 583. 6 kg of p-DCB, 400 kg
of NMP and 1.851 kg of 1,2,4-trichlorobenzene (about 0.25 mole % based on
sodium sulfide) were charged. After pressurizing it to 1 kg/cm.sup.2 G
with nitrogen gas at a liquid temperature of 150.degree. C., the
temperature was raised. After the liquid temperature reached 230.degree.
C., water was sprinkled on the upper external part of the autoclave to
cool the gas phase part of the autoclave. Subsequently, the temperature
was raised to 260.degree. C. and maintained at that temperature for three
hours. Then the temperature was lowered and, at the same time, the
sprinkling of water was stopped. The maximum pressure during the reaction
was 8.82 kg/cm.sup.2 G.
The slurry obtained was filtered and washed with warm water repeatedly in a
conventional method, and then dried in an oven of 120.degree. C. for 5
hours to obtain a white powdery product. The weight average molecular
weight of the polyphenylene sulfide thus obtained was 53,800. The
conversion was 98.7%. Thiophenol was not detected in the reaction product.
COMPARISON EXAMPLE 7
The same procedure as in Example 9 was repeated with the exception that the
sprinkling of water on the upper external part of the autoclave was not
conducted. The maximum pressure during the reaction was 10.5 kg/cm.sup.2
G. The weight average molecular weight of the polyphenylene sulfide thus
obtained was 32,500. The conversion was 99.3%. It was found that
thiophenol was present in a concentration of 150 ppm in the react ion
product.
COMPARISON EXAMPLE 8
The same procedure as in Example 9 was repeated with the exception that the
amount of 1,3,5-trichlorobenzene was 326.8 g (1.6 mole % based on sodium
sulfide). The maximum pressure during the react ion was 8.70 kg/cm.sup.2
G. The polyphenylene sulfide thus obtained was not completely dissolved in
1-chloronaphthalene and, therefore, the molecular weight could not be
determined. The conversion was 98.6%. Thiophenol was not detected in the
reaction product. It was impossible to determine a melt viscosity at
300.degree. C. because of too high viscosity.
COMPARISON EXAMPLE 9
The same procedure as in Example 10 was repeated with the exception that
83.8 kg of water was distilled off during the dehydration step (the
content of water remained being 1.75 moles per mole of sodium sulfide) and
that the sprinkling of water on the upper external part of the autoclave
was not conducted. The maximum pressure during the reaction was 13.7
kg/cm.sup.2 G. The polyphenylene sulfide thus obtained was brownish white
powder. The weight average molecular weight was 18,400 and the conversion
was 99.6% It was found that thiophenol was present in a concentration of
1,120 ppm in the reaction product.
COMPARISON EXAMPLE 10
The same procedure as in Example 13 was repeated with the exception that
the coolant was not passed in the coil attached to the upper external part
of the autoclave. The maximum pressure during the reaction was 10.8
kg/cm.sup.2 G. The polyphenylene sulfide thus obtained was little brownish
white powder. The weight average molecular weight was 33,600 and the
conversion was 99.2%. It was found that thiophenol was present in a
concentration of 140 ppm in the reaction product.
COMPARISON EXAMPLE 11
The same procedure as in Example 13 was repeated with the exception that
1,2,4-trichlorobenzene was not added. The maximum pressure during the
reaction was 8.69 kg/cm.sup.2 G. The weight average molecular weight of
the polyphenylene sulfide was 42,800. The conversion was 99.2%. Thiophenol
was not detected in the reaction product.
EXAMPLE 16
In a 150 liters autoclave as shown in FIG. 1 were charged 19.478 kg of
flaky sodium sulfide (Na.sub.2 S content of 60.1% by weight) and 45.0 kg
of NMP. The temperature was elevated to 204.degree. C. in a flow of
nitrogen under stirring to distill off 5.072 kg of water (the content of
water remained being 1.0 mole per mole of sodium sulfide). The autoclave
was then sealed and cooled to 180.degree. C., in which 22.050 kg of p-DCB,
18.0 kg of NMP and 217.7 g of 1,2,4-trichlorobenzene (about 0.80 mole %
based on sodium sulfide) were charged. After pressurizing it to 1
kg/cm.sup.2 G with nitrogen gas at a liquid temperature of 150.degree. C.,
the temperature was raised. Stirring was continued at a liquid temperature
of 205.degree. C. for two hours, while a coolant of 20.degree. C. was
passed in a coil which was attached to the upper external part of the
autoclave to cool the gas phase part of the autoclave. Then, the
temperature was raised and stirring was continued for three hours with the
liquid temperature being maintained at 265.degree. C. Subsequently, the
temperature was lowered and, at the same time, the cooling of the upper
part of the autoclave was stopped. The maximum pressure during the
reaction was 9.65 kg/cm.sup.2 G.
The slurry obtained was filtered and washed with warm water repeatedly in a
conventional method, and then dried in an oven of 120.degree. C. for 5
hours to obtain a white powdery product. The weight average molecular
weight of the polyphenylene sulfide thus obtained was 97,500. The
conversion was 99.4%. Thiophenol was not detected in the reaction product.
Evaluation of Processability
Spinnability was determined on the polyphenylene sulfides prepared in the
above Examples 9 and 13 and Comparison Examples 7 and 8 as follows:
using a type IB capillograph (Toyo Seiki Seisakusho, L/D=10/1), the
polyphenylene sulfide was melted at 320.degree. C. and the strand from a
die was wound at a predetermined constant speed, while a tension on the
strand was determined.
Similar procedure was carried out with the winding speed being increased
continuously and gradually from 5 m/min. The results are as shown in Table
1.
The polyphenylene sulfides having a high molecular weight prepared in the
above Examples showed stable melt tension and less thread breakage in a
wide range of a winding speed. Accordingly, they are judged to be suitable
for fiber spinning and blow molding applications.
TABLE 1
______________________________________
Speed range for
Melt stable winding
Spinn-
Sample Mw tension* (g)
(m/min) ability
______________________________________
Ex. 9 81,600 4.8 20-60 good
Ex. 13 60,800 2.2 15-60 acceptable
Comp. Ex.
32,500 <0.4 20-60 unsuitable
Comp. Ex.
unable 19.8 broken unsuitable
8 to de- at 5
termine
______________________________________
*The winding speed was 40 m/min. in Examples 9 and 13 and Comparison
Example 7; and 5 m/min. in Comparison Example 8.
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